from time import time,localtime,sleep

class Clock(object):
    """数字时钟"""

    def __init__(self,hour=0,minute=0,second=0):
        self._hour=hour
        self._minute=minute
        self._second=second
    @classmethod
    def now(cls):
        ctime=localtime(time())
        return cls(ctime.tm_hour,ctime.tm_min,ctime.tm_sec)

    def run(self):
        """走字"""
        self._second+=1
        if self._second ==60:
            self._second=0
            self._minute+=1
            if self._minute==60:
                self._minute=0
                self._hour+=1
                if self._hour==24:
                    self._hour=0

    def show(self):
        """显示时间"""
        return '%02d:%02d:%02d' % \
            (self._hour,self._minute,self._second)
def main():
    clock = Clock.now()
    while True:
        print(clock.show())
        sleep(1)
        clock.run()
if __name__=='__main__':
    main()